Reinforced plastic molds



Oct. 27, 1964 K. c. 'scHMocKl-:R 3,153,835

REINFORCED PLASTIC MOLDS Filed Aug. 8, 1962 INVENTOR. KARL C. SCHMOCKERG14 e VM w 'l AT TORNE Y.

United States Patent O 3,153,835 RElNFRCEl) PLASTC MGLDS Karl C.Schrnoclrer, 1% Ward St., Norwalk, Conn. Filed Aug. 8, 1962, Ser. No.215,66@ 9 Claims. tCi. 2S- 131) This invention relates to forms usefulin the construction and related industries, and more particularlyconcerns molds used in forming poured concrete structures and componentparts thereof.

Plywood forms commonly used for poured concrete are not suitable forcontoured or irregularly shaped surfaces, nor do they produce smooth,non-grainy finishes on exposed concrete surfaces. In most cases knownforms leave ragged edges and parting lines, thus requiring sandblastingor other finishing operations. Known methods for the pouring of concretestructures with irnproved surface finish, clean parting lines, andwithin the limits of relatively close tolerances, require productioncenters with highly specialized heavy equipment, machinery, and the useof heavy steel-reinforced molds fitted to the equipment. The completemolded concrete units must then be transported over greater or lesserdistances from the production center to the building sites atsubstantial expense and with the risk of damage in transit.

An object of this invention is to provide improved mold forms ofsubstantially rigid but relatively light-weight construction suitablefor assembly and/or use near or at the building site and effective toproduce precisely dimensioned concrete structures in plain, contoured orirregular shapes and with exposed surfaces produced directly in anydesired finish.

With plywood forms or forms of a similarly suitable material, it is nowproposed to provide the same with an improved reinforced plasticsurfacing bonded thereto, together with structural features forproviding supplemental locking of the plastic surfacing to the plywoodbase and t e further provision of means for preventing delamination ofthe plywood or other laminated base.

A further object of this invention is to provide molds in laminar formwith facing portions which produce evenly fiat or pre-determined shapesof regular or irregular contour in poured concrete and reproduce anydesired surface finish thereon.

Another object of this invention is to provide for the pouring ofconcrete, improved molds capable of repetitive assembly and disassembly,singly or in interfitting and interlocked groups, and capable ofwithstanding relatively high pressures and impacts during pouring andvibrating operations; such molds of laminar construction combiningplywood or other laminated backing, plastic facing, and intermediatereinforced plastic bodies in a structure which results in a monolithicbeam-type construction of the plastic body together with locking andinterlocking features, which yield substantial strength and highresistance to delamination of the plywood and/ or the plastic Iarninae.

Other objects of this invention will in part be obvious and in parthereinafter be pointed out.

In the drawing, FIGURE 1 is a partial transverse section of a moldelement embodying the invention;

FGURE 2 is a plan view thereof;

FGURE 3 is a sectional view showing a detail thereof;

FGURE 4 is a plan view thereof;

FIGURE 5 is a perspective view of a modified form of reinforcement.

it is understood that the molds of the instant invention are primarilyof the type used in pouring substantial concrete building structures, orportions thereof, as for example, walls, arches, floors, and the like.The molds are supported and shored in a conventional manner Friceaccording to the volume of concrete to be poured and they do not utilizegrease or similarly heavy and undesirable releasing aids as is usuallyapplied to known steel or plywood forms.

FGURE l illustrates a portion of a flat mold made in accordance with theinvention. Thus, on a table T there is disposed a pattern sheet with apre-determined surface nisn 11 uppermost which is to be reproduced inthe finished poured concrete structure. Pattern sheet 1t? may be ofwood, plaster, resin, resin impregnated paper, fabric, and the like. Asa preliminary step to mold production, the surface 11 is sprayed with auniformly thin coating of a conventional release agent, not shown.

A uniform coating 12 of a polyester resin is applied over the releaseagent coating to a thickness of about 0.15 to .020; the polyester resinembodying, in addition to the conventional catalyst such as methyl ethylketone, a residual type of catalyst such as benzoyl peroxide in anamount of at least .5% by weight of the resin and a further inclusion ofpowdered electric conductive material such as carbon black in suspensionand in an amount of from 0.5 to 2.6% based on the weight of resin.Coating 12 is then allowed to cure at about 70 F. for about one hour, toabout 80% to 96% of complete cure.

A glass liber mat 13 weighing about l to 11/2 oz. per square foot andsaturated with conventional catalyzed polyester resin is fitted overresin coat 12; residual air bubbles and excess resin are removed fromthe combination by squeegee or the like to maintain from about 25- 40%glass fiber content by weight. Care is taken to maintain such ratio andfreedom from air bubbles in corner regions which, if necessary, aresupplied with additional shredded glass iibers or fiber strands topreclude the forming of voids during the cure which takes place at thisstage at about F. to produce an Sil-90% cure of the resin impregnant ofthe mat.

A glass fiber mat 14 impregnated with conventional catalyzed polyesterresin and similar to mat 13 is applied over the incompletely cured mat13.

The laminate consisting at this stage of partially cured resin coat 12,partially cured resin impregnated mat 13, and uncured resin impregnatedmat 14, is not immediately subjected to further curing. After entrappedair and excess resin have been removed from mat 14 as heretoforementioned, strips of glass ber rnat 15 saturated with catalyzedpolyester resin are laid over mat 14, and entrapped air and excess resinare removed. Mat strips 15 are preferably between 16 and 20 wide whenused in large at areas, otherwise are cut to fit the contours and shapeof the mold, including provision for 2" `to 21/2" wide overlap regionson each side which form part of the beam-type reinforcement constructionas will become apparent in the further description. The strips 15,whether straight or contoured, correspond to strips 16 of 3A plywood orother suitable material which are laterally related and spaced about 1/8to 3/16" and are disposed over the part or parts of the mold which areto be heavily reinforced. Strips 16 are of reduced width and length sothat marginal portions of strips 15 may be folded over the side and endedges of strips 16.

Thus, lateral edge portions 17, 1S of strip 15 extend about the edges19, 2li of plywood strip 16 with the marginal portions 21, 22 of ystrip15 disposed over the margins of exposed surface 23 of plywood strip 16and extended towards each other. lt is understood that as many matstrips 15 and corresponding plywood strips 16 are used as may benecessary to cover the total reinforcement area, and that the individualystrip assemblies are moved under slight pressure towards each other tobring them into abutting relation, as shown in FlGURE l, with the spacebetween plywood strips 16 solidly filled with glass ber reinforcedplastic as shown. AIt is under- 3 stoodthat marginal end portions ofiiber strip 15 are similarly folded about the ends of plywood strips 16.

Batten strips 24 of fiberglass roving or cloth about "-6 wide are laidover the joints formed by and over the adjacent marginal portions 21, 22of strips 15. Strips 24 are impregnated with catalyzed polyester resin,and entrapped air and excess resin are removed. The assembly thusproviding reinforced plastic I-beams which are continuous with thereinforced plastic mold portions; form an integral part thereof, and areabutted by plywood strips 16 which are thus locked in place while theweb portion of the plastic I-beam is locked in between the plywoodstrips.

The assembly described above may be provided with additionalreinforcements for the attachment thereto of conventional shoring,supports, alignment means or the like. In such case, as shown in FIGURE3, the plywood strips 16 are, prior to placement on mat strips 15,provided with thimbles 25 at spaced intervals along a predeterminedextent of the desired reinforcements. Thimbles 25 are threaded for thepurpose later described. Care is taken to irnbed the thimbles wellwithin the plywood strips and to fill any void with resin impregnatedshredded berglass to preclude pressure against the said facing layer oran air pocket between that layer and the plywood. Before further stepsare taken toward assembly, the laminate mold structure is subjected topressure, such as may be produced by clamping devices, or other pressureor vacuum systems. The resin coating 12 and resin impregnated mats 13,14, as Well as strips 15, 24 have been sequentially cured as previouslydescribed. The assembly, with or without thimbles 25, is then subjectedto a conventional post-cure at about 110 to 120 F. and thus the entirelaminate is substantially stabilized with a minimum, if any, distortionor imperfection of the resin molding surface l2 which is highlyresistant to damage by alkali emanating from the poured concrete. Thecured assembly may now be removed from table T, being stripped away frompattern sheet 10.

When the assembly is to be provided with further reinforcements, andthimbles 25 have been previously located on plywood strips 16, thenstuds 26 are screwed into thimbles 26 and beams 28, such as 2 x 4s orthe like, are bored at longitudinally spaced intervals to receive studs26. Nuts 27 on the upper ends of studs lock the beams 23 in placeagainst the rear surfaces of plywood strips 16. It is understood thatbeams 28 may be arranged in various grid patterns as desired ornecessary to cope with expected stresses and alignment conditions. It isalso understood that when such reinforcing members are used and may beexposed to water or dampness, then the exposed surfaces thereof arecoated with lsuitable water repellent material.

In lieu of the above described solid beam reinforcements 28, analternative reinforcement in accordance with this invention takes theform of a channel of reinforced plastic, of inverted U or V crosssection, as illustrated in FIGURE 5, wherein a preformed ilexible stripof urethane foam 29 or similarly suitable material is positioned andsuitably fastened to the rear of the laminar mold previously described,in grid patterns, including curved and variously shaped sections. Strip29 then is covered with one or more layers 30 of curable resinimpregnated fiber mat including flange portions31, 32 which are bondedto the mold proper. The reinforcement is then bonded inplace and curedtogether with the laminar mold during the last cycle of the sequentialcuring resin operations prior to the final cure of the overall assembly.

The preliminary partial cure of the resin impregnated fiberglasslaminates, performed sequentially as the assembly of the moldprogresses, insures minimal internal strains and correspondinglydesirable surface conditions for the production of finely grainedconcrete cement structures. On relatively large surfaces, of 20 squarefeet or more, the catalyzation of the resin and its application duringthe production process is varied whereby the catalytic action in atleast two predetermined areas is more active than in other areas, andthe strains and shrinkage resulting from the first occurring curingprocess are diverted into areas of somewhat later curing to precludeundesirable transmission of buckling or warping forces between oppositeedges or corners.

While various changes might be made in the embodiments of the inventionherein disclosed without departing from the spirit thereof, it isunderstood that all of the matter herein shown or described shall bedeemed illustrative and not by way of limitation except as set forth inthe appended claims.

What is claimed is:

l. A form member of extended surface area for poured concrete structurescomprising a laminate including a facing layer of synthetic resin, aplurality of laterally related plywood reinforcing strips for backingsaid resin facing layer, and resin impregnated glass fiber structuresbetween said strips and said facing and in bonded relation thereto, saidfiber structures including marginal portions extending about the edgesand marginal portions of said strips.

2. A form member for poured concrete structures comprising a laminateincluding a facing layer of synthetic resin having a patterned outersurface, resin impregnated glass fiber structures having at outersurface portions thereof in bonded relation to the inner surface of saidfacing layer, plywood strips overlying inner fiat surface portions ofsaid fiber structures and bonded thereto, said ber structures includingmarginal edge portions thereof wrapped about the lateral edges of saidstrips and bonded thereto.

3. A form member as in claim 2 wherein said glass fiber structurescomprise a plurality of mats in side by side relation, a plywood stripassociated with each mat, the marginal edge portions of each mat beingwrapped about the marginal edges of the associated strip, and glassliber strips overlapping adjacent oppositely extending marginal edgeportions of adjacent rovings and in bonded relation thereto.

4. A form member for poured concrete comprising a smooth finish facinglayer of synthetic resin, plywood reinforcing for said facing layer andincluding a plurality of plywood strips having their lateral edges inadjacent relation to each other, resin impregnated glass fiberstructures in bonded relation to said facing and said plywood strips,said fiber structures including resin impregnated glass fiber incontacting relation with said resin facing, resin impregnated glassfiber mat in contacting relation to said fabric, and a plurality ofresin impregnated glass fiber mats in side by side relation, each mathaving marginal portions thereof wrapped about the edges of anassociated plywood strip, the marginal portions of adjacent mats havingabutting portions, and resin impregnated fiber strips in bonded relationto the rear surface of marginal portions of adjacent plywood strips,said fiber strips overlying marginal edge portions of adjacent firstmentioned mats.

5. A form member as in claim 4 and further including elongatedreinforcement members disposed over the rear surface of said plywoodstrips and means for securing said reinforcement members to said plywoodstrips.

6. A form member for poured concrete comprising a laminate including afacing layer of synthetic resin having a thickness of from about .015 toabout .020, a resin impregnated fiber glass backing layer for saidfacing layer, and, reinforcing strips overlying said backing, saidbacking layer comprising a plurality of adjacent mat strips respectivelyunderlying said reinforcing strips, said mat strips including marginalportions wrapped about the edges of said reinforcing strips.

7. A form member for poured concrete comprising a laminate includingjafacing layer of synthetic resin having a predetermined outer finish, aplywood backing comprising a plurality of laterally adjacent plywoodstrips, a fiber glass layer between said resin facing layer and saidplywood backing, said ber glass layer comprising superposed resinimpregnated mats and resin impregnated mat strips between each plywoodstrip and said mats, said mat strips having marginal portions foldedabout the marginal edges of said plywood strips, the resin impregnatedmats and mat strips being cured in situ.

8. A form member for poured concrete structures comprising a laminateincluding a facing layer of synthetic resin, a plurality of laterallyrelated reinforcing strips, and resin impregnated glass liber structuresbetween the said strips and said facing layer and in bonded relationthereto, said ber structures including portions extending about theedges and marginal portions of said reinforcing strips in interlockingand mutually reinforcing relation.

9. A form member for poured concrete structures comprising a laminateincluding a facing layer of cured synthetic resin, a plurality oflaterally related reinforcing strips in opposed relation to the rearsurface of said facing layer, and a ber reinforced synthetic resin bodybonded to said strips and said facing layer, said resin body includingportion of I-bearn section between adjacent edge 10 portions of saidreinforcing strips.

Wells Apr. 14, 1925 Sperry May 11, 1948

1. A FORM MEMBER OF EXTENDED SURFACE AREA FOR POURED CONCRETE STRUCTURESCOMPRISING A LAMINATE INCLUDING A FACING LAYER OF SYNTHETIC RESIN, APLURALITY OF LATERALLY RELATED PLYWOOD REINFORCING STRIPS FOR BACKINGSAID RESIN FACING LAYER, AND RESIN IMPREGNATED GLASS FIBER STRUCTURESBETWEEN SAID STRIPS AND SAID FACING AND IN BONDED RELATION THERETO, SAIDFIBER STRUCTURES INCLUDING MARGINAL PORTIONS EXTENDING ABOUT THE EDGESAND MARGINAL PORTIONS OF SAID STRIPS.